Preliminary results from an ongoing Phase 1 clinical trial indicate that carfilzomib (Kyprolis), a new proteasome inhibitor, has significant thera­peutic results in patients with re­lapsed myeloma. The Multiple Myeloma Research Consortium (MMRC) reported the results at the Joint ECCO 15-34th ESMO Multidisciplinary Congress, which was held in Berlin from September 20 to 24.

Carfilzomib selectively induces cell death in cancer cells by blocking the activity of proteasomes, which are enzymes that break down proteins. Carfilzomib is similar to Velcade (bor­tez­o­mib), the first proteasome inhibitor approved for multiple myeloma treat­ment. However, car­filz­o­mib reduces periph­eral neu­rop­athy, the pain and numbness in patients’ hands and feet, as compared to Velcade. Carfilzomib is also a more selective thera­peutic agent – it results in fewer or less severe side effects than Velcade.

The current Phase 1 trial presented at the Berlin conference enrolled 31 multiple myeloma patients. Seventeen of the participants had pre­vi­ously received Velcade, of which 15 had re­lapsed after an au­tol­o­gous stem cell trans­plant. All 31 patients received a dose of 20 mg/m² car­filz­o­mib on days 1, 2, 8, 9, 15, and 16 in a 28-day cycle for up to 12 cycles, and 4 mg of dexamethasone (Decadron) was admin­istered prior to each car­filz­o­mib dosage in the first cycle.

At the time of the September conference, the 31 patients had received an average of 6.6 treat­ment cycles, with 11 patients receiving all 12 cycles without any evidence of disease pro­gres­sion. The most common side effects observed in patients were fatigue (61 per­cent), nausea (58 per­cent), and vomiting (36 per­cent).

Researchers noted that more than 30 per­cent of patients who responded to car­filz­o­mib tolerated full-dose ther­apy without disease pro­gres­sion for at least one year. These initial data suggest that car­filz­o­mib may potentially be used in multiple myeloma treat­ments as an alter­na­tive to the current proteasome inhibitor, Velcade. Future clinical trials may evaluate a head-to-head comparison of car­filz­o­mib and Velcade to determine which treat­ment is more effective for multiple myeloma patients.

For more in­­for­ma­tion, please read a press release on the Phase 1 trial results. or see abstract 9201 from the ECCO-ESMO Conference.